Ever wanted to know just how UNIX works and what its doing when you use it? Ever wanted to know a bit more about the people and the evolution of UNIX? If so, this is the book for you. Although somewhat aged now, it still contains enough factual and apropriate material for any undergraduate or postgraduate Degree study of UNIX. In fact I would rate this book as the most important in my Computer Science degree - and it certainly didnt let me down! The book starts with a look at the more basic aspects of the OS, its history and how it appears to traditional users. Then the book moves deeply into the internal fundamentals of how it works by examining the file system structure, memory addressing, scheduling algorithms (it even lists snippets of the source code!), security etc. It then winds up with some basics on distrubuited systems. Although it lacks information on things such as nfs, nis, PAM etc it is arguable that these are services added onto a core UNIX environment and consequently not really apropriate for this book. Modern changes to kernels such as modular UNIX however are not covered as a result of its age. Any decent system administration book would cover off these extra topics and maybe one day we can persuade Maurice to update his excellent work.